Alternatives to Sinemet????

My mother was recently diagnosed with PD and was presribed Sinemet. After 3 weeks of taking it, she was nauseous and exhausted all the time. Her neurologist took her off it today and referred her for physical therapy. The doc said that her body was rejecting it and that she would perhaps try again with a lower dose in a few weeks and attempt to increase the dose over time. Is PT an effective alternative???? The doc also said that she is displaying only a few symptoms of early PD and that her natural dopamine is still mostly in tact. Is there a medicine alternative to Sinemet???
Advice is greatly appreciated!!